1. Field of the Invention
The present general inventive concept relates to a method of manufacturing an inkjet print head. More specifically, the present general inventive concept relates to a method of manufacturing an inkjet print head that includes an improved process to form an ink feed hole.
2. Description of the Related Art
Inkjet print heads print an image by which fine droplets of a printing ink therein are discharged at the desired positions on a printing sheet. Such an inkjet print head is divided into a thermal print type and a piezoelectric print type, based on the discharge mechanism of ink droplets. The thermal inkjet print head generates bubbles in an ink via a heating source and discharges ink droplets by an expansion force of the generated bubbles.
General thermal print heads include an ink feed hole for supplying an ink, a substrate provided with a heater for heating the ink on the surface thereof, a flow passage formation layer, which is arranged on the substrate and forms a flow passage and an ink chamber, and a nozzle layer, which is arranged on the flow passage formation layer and is provided with a nozzle corresponding to the ink chamber.
To manufacture such an inkjet print head, a binding method and a monolithic method are commonly used. The binding method is carried out by separately producing a substrate and a nozzle layer, aligning the substrate and the nozzle layer, and attaching the substrate to the nozzle layer via a polymer thin film. Meanwhile, the monolithic method is carried out by directly forming a flow passage formation layer and a nozzle layer on a substrate. The monolithic method eliminates a necessity of an adhesive demanding the strict requirements as well as alignment operation of the nozzle layer and equipment required to perform the alignment, thus having advantages of reduced production costs and increased productivity, as compared to the binding method.
FIGS. 1A through 1F are views illustrating a conventional monolithic print head manufacturing method. As illustrated in FIG. 1A, flow passage formation layers 2 are formed on a substrate 1, on which heaters 1a for heating an ink and electrodes 1b for supplying an electric current to the heaters 1a are arranged, by photolithography. As illustrated in FIG. 1B, regions where there is no flow passage formation layer 2 on the substrate 1 are filled with a photoresist, thereby forming sacrificial layers 3. As illustrated in FIG. 1C, a nozzle layer 4 provided with a nozzle 4a is formed on the resulting structure including the flow passage formation layers 2 and the sacrificial layers 3. The nozzle layer 4 is formed by photolithography, which is the same method as in formation of the flow passage formation layers. As illustrated in FIG. 1D, an etching mask 5 used to form an ink feed hole is formed. As illustrated in FIG. 1E, the substrate 1 is etched to form an ink feed hole, such that the ink feed hole passes through the rear side of the substrate 1 exposed through the etching mask 5. The etching of the substrate 1 is carried out by dry etching using plasma. The etching mask 5 is removed and the sacrificial layers 3 are removed by using a solvent, thereby obtaining an inkjet print head as illustrated in FIG. 1F.
In the conventional method, the formation of the ink feed hole 1c is carried out by placing a wafer in dry etching equipment and performing a process on each wafer. Accordingly, the method has a disadvantage of deterioration in productivity. In an attempt to improve productivity, an increase in number of the dry etching equipment has been used, but this increase in equipment has a limitation due to high-priced equipment.
In addition, the ink feed hole 1c formed by dry etching has a narrow width, thus making it difficult to obtain the desired ink supply performance.